This invention relates to electric power distribution systems and more particularly to bus duct where a plurality of stacked insulated bus bars are supported in an elongated housing.
Normally, bus duct comprises a plurality of generally flat insulated bus bars supported in a housing that is drawn together to mount the insulated bus bars in a compact sandwiched relationship. The insulated bus bars are supported as a stack set. An elongated housing generally comprises a pair of oppositely disposed housing members that are drawn towards each other against the flat faces of the outer insulated bus bars of the stack set, to support the stacked set of insulated bus bars in a compact sandwiched relationship between the housing members. In accordance with prior art practice it has been found desirable to utilize a construction in which the insulated bus bars are maintained in a sandwiched relationship with the bus duct housing because of the very efficient heat dissipation which can occur and the low voltage drop present per unit length. However, with the commonly used insulating material it has been found that the insulated bus bars when sandwiched together under a slight pressure tend to stick together. If the insulated bus bars stick together when relative movement of the insulated bus bars occur, due to thermal expansion, the primary insulation surrounding the bus bars can be damaged causing the bus duct to fail under some operating conditions. Failure of the primary bus bar insulation can lead to the bus duct section being damaged or destroyed.